Bulk cargo may be transported over long distances using various modes, such as ship, truck or railcar. Typically, the cargo is transported in rectangular, box-like containers that may be permanently connected to a wheeled chassis (such as in the case of a truck trailer or railcar), or may be independent containers that can be temporarily fixed to and transported on a railcar or truck chassis. The independent containers, referred to as intermodal containers, allow for a single load to be transported by multiple modes, e.g., truck and rail, without moving the cargo from one container to another. These containers are also used to transport cargo by ship, where several containers are often stacked on atop the other.
Over time, standards have developed to help ensure that intermodal containers are compatible with the various modes of shipment. For instance, the length and width of intermodal containers must comport with the railcar or trailer chassis on which they will be hauled, attachment points must be properly positioned for mating, and the container height must allow for passage under overpasses or through tunnels while in transit. In addition, it is desirable that intermodal containers be of standard exterior dimensions so as to conserve space and provide load stability when positioning and stacking the containers on ship decks or in storage yards. The standard intermodal container is shaped like a rectangular box having a length of forty feet (˜12 meters), a width of eight feet, and providing structural lift and stack points at each of its eight corners. These points, referred to herein as the Forty Foot Points, correspond to a standard position used by overhead cranes throughout the shipping industry to move cargo containers. Though intermodal containers may be longer than forty feet (some European containers are now 45 feet (˜14 meters) long, while many North American containers are 53 feet (˜16 meters) long), the longer containers still provide structural fitments for lifting and stacking at the Forty Foot Points.
Intermodal standardization has lead to efficiencies in the logistics industry. For example, certain high-speed rail lines are dedicated to transporting dual-stacked intermodal containers because of the amount of cargo they can contain in a stacked configuration. While it may take cargo in a rail boxcar two weeks to travel from Chicago to the West Coast of the United States, the same cargo loaded on intermodal cars may be there in a two days.
However, the inevitable need to relocate empty intermodal containers is not efficient, because the containers take up as much space empty as they do full. Even when empty, each container usually requires its own trailer chassis for highway transport, because just two standard containers stacked together would be too high for truck transport. At most, rail well cars can only move two standard intermodal containers at once, regardless of whether they are full or empty. Thus, it costs nearly as much to haul an empty container as a full one, but without the revenue from the transport of cargo to offset the cost. Even if container relocation is unnecessary, the empty containers still present a disadvantage in that they take up just as much space when stored in a yard as do full containers. In addition, conventional intermodal containers must be loaded and unloaded one pallet at a time by a forklift that enters and exits through one end of the container. Not only is this a slow process that presents spatial constraints to the forklift operator, it does not allow for the loading of lengthy materials such as pre-formed steel beams, lumber, or other materials not suitable for palletizing.
Flatbed trailers and railcars solve some of these problems because a flatbed can be efficiently loaded from any direction, and can accommodate loading of items as lengthy as the flatbed itself. Flatbeds can also be efficiently stacked when not in use. However, flatbeds are not used for intermodal transport because they cannot be stacked when loaded, and do not provide the requisite structural fitments at the Forty Foot Points for lifting by an overhead crane. Rather, traditional flatbeds are permanently affixed to a trailer or railcar chassis, requiring that cargo transported by flatbed be moved from one flatbed to another in order to continue transport via another mode.
A solution to this problem is to enhance the traditional flatbed design by providing it with structural members at the appropriate lift positions, but allowing those members to collapse or be removed when the flatbed is to be stored or relocated. Though such designs have been attempted, they have not been adopted due to issues with safety, durability and functionality. The collapsible designs that have emerged have been manually operated by removing and hammering in pins, have involved manual installation of structural members, and/or have allowed gravity to slam heavy components together. Though springs and counterweights have been used to assist with manual manipulation, the high level of operator involvement lends to safety hazards and is very time consuming. Moreover, the necessity of structural fitments at the Forty Foot Points conflicts with the desire to enable side and/or top loading of large materials. Thus, there is a desire to move the structural members out of the way to allow for full-length, full-width loading, but then back into place prior to transport. This is preferably done without enabling components to extend laterally beyond the side envelope of the flatbed, as this could cause a safety hazard in transit should a component come unpinned. Prior art collapsible intermodal designs have been functionally limited to forty-five feet of usable deck length.
Finally, prior art attempts at intermodal flatbeds have been limited in the amount of load they can support during lifting operations. By removing the side walls and top of a traditional intermodal container, the tensile load during lifting is fully concentrated at the points along the flatbed where the structural members connect. This point loading can lead to deformation of the flatbed if it is not sufficiently strong. Though the flatbed can be made stronger by adding more steel, this adds weight to the empty load. A heavier empty weight results in less cargo carrying capacity because government weight restrictions on total weight will be reached with less cargo. Despite these issues and challenges experienced in connection with prior art attempts to provide a collapsible intermodal solution, there remains a long felt need for a suitable intermodal transport platform for the logistics industry.